This invention relates to the field of dry diving suits or apparel, and more particularly to improvements in venting valves or devices forming part thereof.
Dry suits are those that maintain a dry interior. They are preferred in those instances where thermal protection is most needed and is achieved by insulative liners that become less effective when wet. Such suits often include removable, thermally protective gloves that likewise are intended to remain dry.
Ideally, when a dry suited diver is at a given depth, the ambient pressure on each portion of the suit is balanced by a like pressure within, with the volume of the suit and its gloves adjusted for comfort, mobility, and buoyancy. When the diver ascends to a shallower depth, the ambient pressure decreases relative to the suit interior and, unless vented, the interior gas tends to expand the suit and its gloves with resultant undesirable increases in volume and buoyancy and, in some cases, blowing off of the diver's gloves.
Diving suits or apparel have long been provided with vent valves positioned at various locations for the purpose of venting excess gas from the suit proper or from certain zones thereof, such as gloves, so as to maintain a constant volume while excluding entry of water into the suit or zones served by the valves. U.S. Pat. Nos. 2,593,988 and 3,026,522 describe representative prior art valves and the use thereof. In general such valves have comprised flexible rubber valve elements, or spring biased elements that yield to expansion of gas due to pressure differentials during ascent and that close to seal out water during descent when ambient pressures increase. Such valves have been subject to water leakage in that they have been prone to become fouled by sand or mud, or when they have been allowed to accumulate salt crystals from prior use without subsequent cleaning or flushing with fresh water. Such leakage of water, for example into gloves of the dry type, can be a great disadvantage, particularly when protecting the diver against cold temperatures is a factor. When water gets into the liners of gloves, boots, or other suit portions it materially reduces the insulating value thereof, and the diver's ability to work, or even survive, in extremely cold conditions is impaired.
U.S. Pat. No. 4,234,637 discloses a microporous protective film formed of non-water soluble, non-skin-toxic material for use in protective garments including diver's suits, the porosity of the film permitting the passage of body vapors but preventing, at least up to modest pressures, the counter-passage of water. That patent contemplates the use of such material to form diver's wet suits, having the advantage of being more comfortably worn out of the water than are conventional wet suits.